Moira Gunn recently interviewed him and a colleague about one of his current projects, ZoomAtlas, a geographical wiki with the ability to draw as well as write.
I edited the full interview, excerpting Cunningham's comments on the invention of the wiki, his motivation, and role of wikis (7 min 44 sec).
As you hear in the interview, Cunningham invented the wiki to solve a problem he had. He did not worry about security, because he trusted the members of his community to be responsible.
He sees wikis as doing things that could not be done another way. For example, one could not have created the Wikipedia by paying experts, but it has succeeded as a volunteer community wiki. (The Wikipedia founders first tried to create an online encyclopedia by conventional means and failed).